Home
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
Obsolete Keywords
Keywords that are still supported, but no longer maintained (*) are considered obsolete.
Obsolete Optimization Keywords
Optimization Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
Bulk Data
Optimization Keyword This group of keywords are used to insert Bulk format data into <name>.radopt file.
/BULKFMT (Obsolete)
Optimization Keyword Defines the Format of the intermediate OptiStruct input file during Design Optimization.

Welcome
What's New
View new features for Radioss 2025.1.
Overview
Radioss^® is a leading explicit finite element solver for crash and impact simulation.
Tutorials
Discover Radioss functionality with interactive tutorials.
User Guide
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
- File Extensions and Formats
  Current Radioss format uses the 12x extension format.
- Single File Input
  This format allows running either Starter or Engine with the same file.
- New Keywords in 2025
  New and modified features in Radioss.
- Starter Input
  This manual provides a list of all the model definition keywords and options available in Radioss.
- Engine Input
  This manual provides a list of all the solution definition keywords and options available in Radioss.
- LS-DYNA Input
  This manual provides a list of LS-DYNA input files available in Radioss.
- Multi-Domain
  This manual contains the description of the keywords for the Radioss Multi-Domain.
- Obsolete Keywords
  Keywords that are still supported, but no longer maintained (*) are considered obsolete.
  - Obsolete Starter Keywords
    Block Format Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
  - Obsolete Engine Keywords
    Engine Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
  - Obsolete Optimization Keywords
    Optimization Keyword Keywords that are still supported, but no longer maintained (*) are considered obsolete.
    - Bulk Data
      Optimization Keyword This group of keywords are used to insert Bulk format data into <name>.radopt file.
      - /BULK (Obsolete)
        Optimization Keyword Defines Bulk Format data to be inserted into the intermediate OptiStruct deck during Design Optimization.
      - /BULKFMT (Obsolete)
        Optimization Keyword Defines the Format of the intermediate OptiStruct input file during Design Optimization.
      - /BULKMAT (Obsolete)
        Optimization Keyword Defines Bulk Format Data to be used as the conversion data for Radioss material data (/MAT) into the intermediate OptiStruct input file during Design Optimization.
      - /BULKPROP (Obsolete)
        Optimization Keyword Defines Bulk Format Data to be used as the conversion data for Radioss property data (/PROP) into the intermediate OptiStruct input file during Design Optimization.
    - Design Constraints
      Optimization Keyword In this group, keywords are used to define the design constraints.
    - Design Response
      Optimization Keyword In this group, keywords are used to define the design response in optimization.
    - Design Variables
      Optimization Keyword In this group, keywords are used to define the design variable in optimization.
    - /DEQATN (Obsolete)
      Optimization Keyword Specifies one or more equations for use in optimization.
    - /DESOBJ (Obsolete)
      Optimization Keyword This keyword can be used to select a response as the objective function of an optimization run by selecting a response as the objective function. The selected response can either be minimized or maximized based on the inputs specified on this keyword.
    - /DTABLE (Obsolete)
      Optimization Keyword List of constants to be used in functions defined by /DEQATN.
    - /DVGRID (Obsolete)
      Optimization Keyword Defines the relationship between design variable and grid point location.
    - /ESLPART (Obsolete)
      Optimization Keyword Defines parts in the model which will be included in ESLM optimization.
- Other Files
- Definition
Example Guide
This manual presents examples solved using Radioss with regard to common problem types.
Verification Problems
This manual presents solved verification models.
Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding Radioss.
Theory Manual
This manual provides detailed information about the theory used in the Altair Radioss Solver.
User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.

/BULKFMT (Obsolete)

Optimization Keyword Defines the Format of the intermediate OptiStruct input file during Design Optimization.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/BULKFMT/`fmt`

Definition


Field	Contents	SI Unit Example
`fmt`	FREE (Default) LARGEFREE FIXED LARGEFIXED

Examples

Examples of different OptiStruct deck formats (material and SPC as example) during the Radioss-to-OptiStruct conversion.

fmt=FREE:

MAT1,1,210000.0,,0.3,1.0
SPC1,1,2,91
SPC1,3,3,17
SPC1,2,123,1

fmt=LARGEFREE:

MAT1*,1,210000.0,,0.3
*,1.0,,,
SPC1*,1,2,91,
*,,,,
SPC1*,3,3,17,
*,,,,
SPC1*,2,123,1,
*,,,,

fmt=FIXED:

MAT1           1210000.0             0.3     1.0
SPC1           12             91
SPC1           33             17
SPC1           2123            1

fmt= LARGEFIXED:

MAT1*                  1         210000.                             0.3
*                      1.
SPC1*                  12                             91
*
SPC1*                  33                             17
*
SPC1*                  2123                            1
*